The devastating effects of the Vibrio cholerae produced enterotoxin, choleragen, on the human intestine are well-known, and have been documented in the literature [see for example, N. Hirschhorn et al., Sci. Am., 225, 15 (1971)]. Additionally, enterotoxin produced by certain strains of Escherichia coli has been implicated as being responsible for certain infant and travelers' diarrhea which is characterized by the "cholera syndrome", [see for example, S. L. Gorbach et al., J. Clin. Invest., 50, 881 (1971); R. B. Sack et al., J. Infect. Dis., 123, 378 (1971); H. L. DuPont et al., N. Engl. J. Med., 285, 1 (1971); The New York Times, Section 19, Page 1, June 1, 1975]. This syndrome is characterized by profuse "rice water" diarrhea leading to collapse and possibly to death.
Because the results of V. cholerae and enterotoxigenic E. coli infections are at the least very inconvenient and uncomfortable and at the worst can result in the death of the host, there is much ongoing research attempting to identify and purify the toxins presumed responsible for these effects in order that anti-toxins and/or toxoids may someday be made available to combat their effects. To date, choleragen has been purified and shown to be a portein consisting of two types of subunits [J. J. Lo Spalluto et al., Biochem. Biophys. Acta., 257, 158 (1972)] and E. coli produced enterotoxin has been shown to exist in heat-labile and heat-stable forms [C. L. Gyles, Ann. N. Y. Acad. Sci., 176, 314 (1971) and references cited therein] but E. coli enterotoxin has not yet been characterized as completely as choleragen. The heat-labile form however, has been shown to cross-react with choleragen antibody [D. R. Nalin et al., J. Inf. Diseases, 130, 595 (1974)], thus demonstrating that each antigen may be neutralized, and suggesting that their specific effects may be reduced or eliminated if the proper antitoxin is administered. Because E. coli enterotoxin cross-reacts with choleragen antibody, one might assume that these proteins possess some common structural features.
Taking into account this possible similarity in structure and because a V. cholerae toxoid has been prepared, [Rappaport et al., Infect. and Immum., 9, 304 (1974)], one would expect that an E. coli toxoid can similarly be prepared.
Research in these areas related to V. cholerae and E. coli enterotoxin and their effects would, of course, be facilitated by the production and availability of increased amounts of the enterotoxins.